The present invention relates to a semiconductor device and a method of manufacturing the semiconductor device.
In recent years, in order to make a semiconductor device have a high breakdown voltage, semiconductor devices of various structures are proposed.
Japanese Unexamined Patent Application No. 2004-152979 describes the following semiconductor device. Multiple trenches are formed in a width direction of a channel over a semiconductor substrate of a first conductivity type. A drain drift region of a second conductivity type is formed to surround side faces and a bottom of this trench. The interior of the trench is filled up with an insulator. Moreover, among the multiple trenches, an impurity region of the first conductivity type is formed. Thereby, it is supposed that ON-resistance per unit area can be reduced.
Moreover, Japanese Unexamined Patent Application No. 2007-027641 describes the following semiconductor device. A p-type body region is formed over a p-type semiconductor substrate. An n+-type source region is formed in a surface region of the body region. An n+-type drain region is formed over the semiconductor substrate. An n−-type drift region is formed between the source region and the drain region. A gate insulating film is formed over the body region. A supplementary insulation film is formed over the drift region. A gate electrode is formed in parts on the gate insulating film and the supplementary insulation film. Furthermore, a silicide film is formed over the gate electrode, on the source region, and on the drain region. Thereby, it is supposed that a gate resistance can be sufficiently lowered and a high breakdown voltage can be achieved.
Moreover, Japanese Unexamined Patent Application No. 2008-166717 describes the following semiconductor device. A groove part is formed in an active region over a semiconductor substrate. On top faces of both sides that sandwich this groove part, two polysilicon layers into which impurities of a conductivity type reverse to that of the active region are provided. In the active regions that are placed on both sides that sandwich the groove part and are under the polysilicon layers, two drift layers into which impurities of a conductivity type reverse to that of the active regions are provided. A gate electrode is formed through a medium of the gate oxide film provided over the bottom and the side faces of the groove part. Moreover, in a portion that is not covered with the gate electrode of the two polysilicon layers, a source region and a drain region are formed. Thereby, it is supposed that a high-breakdown-voltage MOSFET can be reduced in size.
Moreover, Japanese Unexamined Patent Application No. 2009-277956 describes the following semiconductor device. Multiple trenches are formed in a stripe manner in a source-drain direction. A source region, a drift region with some distance from it, and a drain region are formed in this order over a top face region sandwiched by the trenches and a side face region. Thereby, it is supposed that a tradeoff relation between a breakdown voltage and an ON-resistance can be improved.